Filament arrangement



1 Feb; 17, 1931. s. E. BROWN FILAMENT ARRANGED-HERE.

Filed Feb. 27, L928 UNITED STATES PATENT OFFICE SUMNER E. BROWN, OI DEDHAM, MASSACHUSETTS, ASSIGNOR TO GENERAL MOTORS CORPORATION, CORPORATION OF DELAWARE FILAMEN'J. ARRANGEMENT Application mea February 27, 1928. Serial No. 257,274.

This invention relates to lighting and has articularly to dowith a bulb and reflector or use in a headlight for an automotive ve-,

hicle, though certain features of theinvention are not limited in their application to light bulbs used in any particular field of lighting. 4

While features of the invention are applicable to bulbs of the single filament type, as

will appear from an inspection of the claims,

. the invention relates particularly to two filament bulbs of the type used in special reflectors such as that disclosed in my application Serial N 0. 20,444, filed April 3, 1925, in which a shift of current from onefilament to the other effects .a raising or lowering of the beam. The arrangement of filaments in the bulb is such as to facilitate manufacture as well as produce a superior light distribution. Thus the filaments are of V-shape, the one a duplicate of the other, and when assembled in the bulb lie in the same plane and are preferably connected tolead-in wires also lying in that plane. This permits the laying of the lead-in wires and filaments in a form of simple construction to insure correct positioning when welding the filaments to the lead-in wires. The use of forms in filaments of simple design permits greater accuracy in filament positioning. This has the important advantage that it renders it possible to dispense with the complicated bulb adjusting devices now universally employed to secure proper focusing of the bulb. This design of filament besides possessing advantages in manufacture also give a superior light distribution. The lower side of the lower filament preferably lies along a horizontal line passing through the focus of the reflector and because of its horizontal position produces a greater concentration of light for the top of the high beam than is produced by conventional designs of filament. The remaining portion of the lower filament is inclined and being located slightly above the focal line and at an inclination throws its light downwardly with a considerabledegree of diffusion which is desirable in the lower portion ofthe beam. The upper portion of the upper filament pref: erably extends horizontally and due to its po- -accordance with my invention.

sition above the focus throws a rather concentrated light upon the adjacent portions.

an unsymmetrical light distribution about a central longitudinal vertical plane passing through the reflector focus. This is accomplished by sovlocating the bulb that the plane containing the filaments extends at an angle to the vertical. This feature obviously is of utility whether a single or a double filament be provided.

Another feature of the invention resides in the provision of a reflector designed to cooperate with the particular arrangement of filaments. It is an object of the invention to design a two filament bulb and reflector which will give a satisfactory straight ahead beam for normal driving and which will move part of this beam both downward and to the right upon a shift in filaments.

Other objects of the invention will appear in the course of the following description, taken in connection with the accompanying drawing and appended claims.

In the drawing:

Figure 1 is a front elevation of the assembly.

Figure 2 is a section through a reflector provided with my improved two .filament bulb indicating the direction of the rays pro jected from the lower filament.

Figure 3 is a section on line 3-3 of Figure 1.

the unsymmetrical light patterns produced with the bulb positioned as shown in F igures 2 and 3.

Figure 5 is a view of the bulb.

Figure 6 is an enlarged view of part of the bulb, showing the arrangement of the filaments.

The reference character 2 indicates'the reflector at the center of which is mounted bulb 4 having filaments arranged-therein in The filaments comprise, a lower V-shaped filament Figure 4 illustrates with some exaggeration 6 having a straight portion 8 and an inclined portion 10 and an upper filament 12 having a straight portion 14 and an inclined portion 16. Portion 8 of the lower filament is secured to lead-in wire 16, portion 14 of the upper filament is secured to lead-in wire 18 and portions 10 and 16 of the respective filaments are for convenience secured to a common lead-in wire 20. The present invention ermits the arrangement of the filaments and lead-in wires in a common plane. This is'an important feature from' the standpoint of accuracy and uniformity in positioning'the filaments in the making of the bulb. In assembly of the filaments the wires 16, 18 and 20and the duplicate filaments 6 and 12 are placed in a suitable form and the ends of the filaments are then welded to the respective lead-in wires.

The reflector which Ihave designed for use with the bulb just described is illustrated in detail in Figure 1. I have shown four lines A, B, C, and D, which when viewed from the front, appear to form substantially a square. The zones of the reflector above the line B and below the line D are inclined downward two or three degrees as indicated by their axis 2424, shown in Figure 2 and the zones on the outer sides of the lines A and C are inclined a similar distance to the right, as viewed from the operators seat. The axis of the zones outside of lines A and CV is indicated by the line 26-26, inFigure 3. The central zone bounded by the four lines A, B, C and D covers that portion of the reflector adjacent and in rear of the parameter and it is this part of the reflector which responds in a material degree to lateral or vertical shifting of the source of light; The axis of the central zone is indicated by the line 22-22, in Figures 2 and 3. In this connection it may be stated that when an ordinar concavo convex reflector is used with ament light bulb and the filaments a two are vertically spaced, a change in the source of light from the lower to the upper fila- 'ment causes a-downward shift of the rays of light from that portion of the reflector in rear of the parameter but does not lower the top line of the beam, because light from the upper filament is thrown higher by the upper and lower parts of the reflector ahead of the parameter than light from the lower filament. This is apparent from an examination of Figure 2. There is a region on either side of the arameter adjacent the top and bottom 0 .the reflector where no noticeable change is efiected by a shift in filaments. In view of these facts,-in order to produce a reflector which will depress the top line of the beam when'a change is made from the lower to the upper filament it is necessary to bend the upper and lower parts of the reflector downward, be the bend far enough in rear of the parameter so that that an unsymmetrical distribution 0 a central longitudinal vertical plane passing through the reflector so that a greater pro-.

While my invention is applicable to 'plain' reflectors used with a fluted lens, I have illustrated a vertically fluted reflector which is used with a plain len's. In the center I have illustrated one wide flute which is plain above the source of light but which is convex or concave in section belowthe source of light. I

As this central flute is wide, the light is spread out as indicated by the full line H in Figure 4, the concavity or convexity of the lower part of thisfiute causing the lower part of the beam from this flute to be wider than the top art. p For purpose of illustration I have exaggerated this feature in Figure 2 in which the dotted lines 30 indicate that the lower part of the central flute is concave. It is .advis: able, though not necessary, to increase the concavity or convexity of this flute from the vertex to the rim in order to secure a umform and gradual spread in the lowerpart of the beam. H

The intermediate beam, indicated by the full line J, is cast by the zones on e outer sides .of the lines A and C. These flutes are about the same size as or slightly narrower than the central flute E-E, but do not spread the light quite so much, due to the fact that they are farther'away from the source ofl ight than the central zone and that the light strikes these flutes a a more acute angle. 4

The hot spot of the pattern, indicated by the full line K, is formed by the central part of the reflector bounded by the lines A, B, C

and D and excluding the central flute E-E. This beam is higher than the rest of the pattern due to thefact that the top and bottomzone just inside line A or line (3,1 have gradually widened the flutes from the central zone.

E E to the lines A and C so that this factor would not enter into the case and cause the beam K to be more intense in the center than at the outside.

- The arrangement which I have ust described produces a light pattern formed from a composite of three separate beams, one

. from each zone of the reflector.

In the use of the filament I find it advantageous 'to arrange the bulb so that, as shown in Figure 1. the filament is inclined to the vertical. This has the advantage of giving light about portion of the light from the bulb and reflector at one side of the vehicle may be thrown toward the side of the roadway than is now the case. In practice I have found it preferable to arrange the lower filament along "the 5 X 1. The combination axis so that a-nearly symmetrical pattern of light, indicated in full lines in Figure 4, will be. rejected when the lower filament is used.

he pattern formed when the upper fila-- ment '12 is energized is indicated 1n dotted lines in Figure 4. The hot spot K is moved downward and to the right to the dotted line position K as this beam is from the central zone which is responsive'to a lateral or vertical shift in the source-of light. The intermediate zone J is from the side zones of the reflector and is moved downward only, as indicated at J, as these zones are ahead of the parameter and are not'res nsive in a material degree to a lateral shi in the source of light.- The beam H is moved to one side, itsintensity being changed slightly in difierent parts by the shift. Its upper and lower lines are lowered only slightly as-the upper and lower zones of the reflector cast their light in the upper part of this beam when the upper filament is energized. v 1

As previously stated, I have also preferably arranged the straight portion of the lower filament along a horizontal line extending through the focus. This portion of the filament projects a strong light for the top of each beam. The inclined-portion of the same filament projects a somewhat difiused light for the lower portion of each beam. The straight upper portion of the upper filament 1 projects a strong light for the lower part of each low beam while the'inclined portion of the same filament projects a difiused light for the high portion of each low beam. T 's arrangement is important as it lessens the likelihood of glare.

The bulb just described is particularly. well 4 designed for accuratelypositioning and can consequentl be used satisfactorily in reflectors havmg fixed sockets. The fact that the filaments are interchangeable is an important feature facilitating manufacture. I have thus produced a-reflector and bulb which, upon a shift'from the lower to the ,upper filament, will lower the u per line of the light pattern and move the le hand edge to the rig of the composite beam materially downward and to the right. Another im rtant feature of my invention resides in t e fact that in the raised patterns the most intense part of each separate zone or beam, referring to the separate zones H, J and K from different positions of the reflector, will be at the top,

while in the lower pattern the-most intensepzrt will be inthe lower part ofeach separate I claim: I i l I bf a concavo convex t and which will move the hot spot reflector com rising a central zone responsive m a matena degree to vertical and lateral shift in the source of light, up er and lower zones tilted to cast the light s 'ghtly downward from the normal and below the light from the central zone, side zones tilted to.

inclined downward rom the normal and side zones inclined to one side from the normal, i

said reflector being provided with a wide central flute for casting a diffused beam and narrow flutes on each side thereof for casting an intense beam, the sides of the reflector on either side of the narrow flutes bein fluted for casting a beam of intermediate width.

In testimony whereof I aflix my si nature.

: SUMNER E. BR WN. 

